From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933312AbdJQHlG (ORCPT ); Tue, 17 Oct 2017 03:41:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51896 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751802AbdJQHlE (ORCPT ); Tue, 17 Oct 2017 03:41:04 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 5C6FFC058EB1 Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=pagupta@redhat.com Date: Tue, 17 Oct 2017 03:40:56 -0400 (EDT) From: Pankaj Gupta To: Christoph Hellwig Cc: kwolf@redhat.com, haozhong zhang , jack@suse.cz, xiaoguangrong eric , kvm@vger.kernel.org, david@redhat.com, linux-nvdimm@ml01.01.org, ross zwisler , linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, linux-mm@kvack.org, stefanha@redhat.com, pbonzini@redhat.com, dan j williams , nilal@redhat.com Message-ID: <1441791227.21027037.1508226056893.JavaMail.zimbra@redhat.com> In-Reply-To: <20171017071633.GA9207@infradead.org> References: <20171012155027.3277-1-pagupta@redhat.com> <20171012155027.3277-3-pagupta@redhat.com> <20171017071633.GA9207@infradead.org> Subject: Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.116.151, 10.4.195.26] Thread-Topic: add virtio-pmem driver Thread-Index: 1juNkDUNPAEL1Bf5k+LD7biC2znxFQ== X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 17 Oct 2017 07:41:04 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > I think this driver is at entirely the wrong level. > > If you want to expose pmem to a guest with flushing assist do it > as pmem, and not a block driver. Are you saying do it as existing i.e ACPI pmem like interface? The reason we have created this new driver is exiting pmem driver does not define proper semantics for guest flushing requests. Regarding block support of driver, we want to achieve DAX support to bypass guest page cache. Also, we want to utilize existing DAX capable file-system interfaces(e.g fsync) from userspace file API's to trigger the host side flush request. Below link has details of previous discussion: https://marc.info/?l=kvm&m=150091133700361&w=2 Thanks, Pankaj